Two rather strange and enigmatic new species of spider — now known as Chaco castanea and Chaco costai — were just discovered living in the South American country of Uruguay. Of the new species more interesting traits is the use of a flap-like door in their burrows that they use to conceal themselves behind, before emerging and ambushing their prey. I guess that it’s roughly the equivalent of coming across a nice, fully stocked empty house, only to have a giant spider emerge from behind a false wall. Sort of sounds like something from a horror movie… 🙂
The two new spider species both reach sizes of roughly 1-2cm in body size, with long robust legs emerging from said body. In line with other Nemesiids their body is itself rather elongated looking, rather than being more compact. Both species were discovered living a range of habitats, but typically in “sandy soils of oceanic and river coastal areas associated with psammophyte, or sand-dwelling, vegetation”. It was in these sorts of environments that the researchers discovered the silk-lined burrows — with their false walls — that the spiders spend most of their lives in. The fact that the spiders rarely emerge — mostly just for mating — helps to explain how the species have remained “undiscovered” until now.
“Due to a number of life history characteristics, these spiders are difficult to collect and consequently little is known about their biology,” notes Laura Montes de Oca, Instituto de Investigaciones Biológicas Clemente Estable, Uruguay. “Observations in natural conditions let us to know that they are mostly active during night. This knowledge is key to finding the spiders in order to perform the necessary studies, both on field and in laboratory. Remaining in the burrow most of their lives, makes these animals vulnerable to habitat perturbations. In Uruguay the psammophyte vegetation is critically decreasing, so it is very important to study and conserve the species”
The press release provides more:
Experiments in laboratory environment reveal some of the secrets that the secluded burrow life of these spiders hide. Chaco costai was observed during hunting, when the spiders lift the entrance of the burrow with their front legs. The flap-like door of the spider den provides a perfect cover to ambush and catch the unsuspecting victim. The spiders return to their burrow after catching the prey. Another occasion when the spiders go in the open is during copulation when both the male and the female leave their hiding places. However, they return to the burrows straight after that.
The new findings were just published in the open access journal Zookeys.